Aging, nutrition and immune function.

Aging is usually associated with increase in chronic disease as well as infections and associated morbidity. This is often thought to be secondary to immunosenescence. Whether this decline in immune function with aging is due to the aging process per se or is secondary to poor health, inflammation, and other life style factors particularly suboptimal nutritional status is discussed. Aging is often associated with dysregulation of immune response even among healthy elderly; some of these changes may be secondary to deficiencies of macronutrients (energy and protein) and micronutrients (notably, vitamins B6, B12, and folic acid as well as iron and zinc). Older individuals often have multiple nutrient deficiencies because of physiological, social and economic factors. Nutrient supplementation is often accompanied by an improvement in immune function particularly in those who are nutrient-deficient. The long-term benefits of multinutrient supplements to healthy elderly not at risk for nutrient deficiencies, however, are currently not well-established. Priorities for future research and methodological considerations for future studies are discussed.